The proposed research will examine three measurement issues in the use of data on sexual, contraceptive, or fertility behavior collected from two or more members of a dyad or family: (1) the extent to which and circumstances under which responses from different dyad or family members constitute multiple indicators of dyad/family variables, or should be interpreted as single indicators of individual variables; (2) the potential bias in analyses that ignore the possibility of correlated error among responses from different dyad or family members; and (3) the potential bias in analyses that ignore the possibility of differential reliability of responses of different dyad or family members. Two sets of data will be utilized to examine these issues. One set consists of husbands' and wives' motivations, intentions and behavior regarding contraceptive use, fertility and wife's employment. The other consists of adolescents' and parents' attitudes and behavior regarding the sexual socialization of the adolescent. Both data sets will be analyzed with Joreskog's LISREL IV computer program to simultaneously estimate structural equation models and their associated measurement models. The results of the research will indicate the seriousness of these measurement issues in population research and will suggest to future investigators the data collection requirements for dealing with these problems. They should also stimulate the reanalysis of other dyad/family data on sexual, contraceptive or fertility behavior, in order to validate and/or modify the results of substantive findings based on them.